This should be a much cleaner option than maintaining libgcc.h by hand. Only
tested on sparc, but it should also cast out the build problems on powerpc.

1) Doesn't work in cross-compiler environment. You confused CC and TARGET_CC

Tbh, when I look in the libgcc.h, excepted the header, it was empty. It seems that the forked sh doesn't known anything
about CC, so I tried:

+ CC=$(TARGET_CC) /bin/sh $< > $@ || (rm -f $@; exit 1)

2) Symbols don't get included into symlist.c so it's unlikely to work.

Well, finaly it doesn't help a lot, the dpkg-build... still failed at the same
place:
_restgpr_29_x in boot is not defined
Just note that it's not any more _restgpr_31_x(), I presume just because nm
list it first?

I'll test on imac g3 today
3) Even if it works it would result in a largely bloated kernel.img due
to unused libgcc routines

Well, whatever src tree (svn 2641, 2642, dpkg 1.9-beta3, 1.9-beta4) which I reach to all build with gcc-4.3, it always
failed to boot:

Welcome to GRUB!
the symbol `__lshrdi3' not found
Aborted. Press any key to exit.
As I am newbe to grub2 (and have few programming knowledge), can you advise me
if it's a well known issue?
Thanks for all effort,
J.